Light Energy and its properties

BY JOEL BOUSEFOR 7 T H GRADE BIOLOGY

10/18 /2012

Light Energy and its properties

For this lesson we wil l learn al l about l ight.We wil l learn: • What it is • How we are affected by it• How l i fe is affected by it• How it is manipulated

-Let’s now discuss what you al l know about l ight.

What We Will Learn

Light Humor

Admit it. When you were younger you:

1) Drew the Sun in the corner of the paper.2) Closed the fridge door really slow, just to see when the lights

went off.3) Used a magnifying glass to fry ants.4) Tried to balance the light switch between the ON & OFF

position. Light is used in many ways;like in this funny video involving a stoplight-

What is Light?

• Light is electromagnetic radiation that is visible to the human eye

• It is made of waves.

• The speed of light is 186,282 miles per second.

•Light takes about 8 minutes to reach earth from the Sun.

•There are many different waves emitted from the Sun like UV rays and x-rays that can’t be seen.

•Light is made up of all different colors.

• The colors we see are the ones that are being reflected.

A video on electromagnetic waves - YouTube

Light is a form of Energy

It can be manipulated and harnessed.

Light of Life

As humans we depend on a steady stream of light energy everyday for many things.

Solar panels harness light energy and converts it into electricity.

This saves billions in costs and helps reduce harmful gas emissions in the environment.

Plants Animals

Plants use light energy as food to live and grow

Some animals, such as corals, also photosynthesize.

Photosynthesis

Light Manipulation

• As light waves are traveling out from the Sun or any source of light, they run into many objects.

• Whenever they hit something, they are either absorbed, reflected, or refracted.

Absorption

When light waves hit an object, they stop and are neither reflected nor refracted.

Example: Wood

When light waves hit a smooth surface they reflect at an angle equal to the angle of the incoming light wave.

Reflection on a Smooth Surface

Example: Mirror

Reflection on a Rough Surface

When light waves hit rough surfaces, they bounce off at many different angles.

Example: Mountainous Regions

When light waves hit certain objects, they go through the object and bend, coming out at different angles.

CPALMS: URL Resource Preview—This will show you how light refracts through different mediums.

Example: Diamond

Refraction

Light Transmission

• Sometimes light waves hit objects, they pass through the object but do not bend or change. • This is the transmission of light.

Now I’m going to name some objects and you guys tell me

whether they absorb, reflect, or refract l ight waves.

Activity